Question

what would happen to life on Earth if the forests disappear

Answer 1

We will die within a day because of lack of oxygen

Answer 2

There would be no life on earth if the forests disappears. A balance between plant and animal life should be maintained for the existence of life in earth. It the forests are cut down,it will lead to soil erosion and most importantly the amoint of oxygen will be insufficient. Oxygen is the basic requirement for all forms of life. So life without forests is not possible.